Songbirds learn their song from external models. The major brain nuclei serving this process have been identified in the canary by a combination of anatomical, physiological, hormonal and behavioral studies. Some of these nuclei, such as the hyperstriatum ventralis, pars caudale (HVc) and robustus archistriatalis (RA) of the forebrain, develop under hormonal influence in parallel with song behavior. Nuclei from the left hemisphere seem to be dominant in song production since lesions to nuclei on that side result in more severe song deficits than right side lesions. Nucleus HVc is especially interesting because it is involved with song perception and production and its size is related to the complexity of the learned song repertoire. The research proposed will map the representation of learned song syllables in nucleus HVc. For this purpose, the P.I. will use a novel multi-electrode array for simultaneous recording of single-unit activity in various parts of the nucleus. These recordings will be made in both left and right HVc during song perception and production in awake, unrestrained birds. This same procedure can be applied to other nuclei in the song control system and to birds whose song behavior is dynamically changing as they learn new song elements or as song recovers following lesions to other parts of the system. The results obtained with this new electrode configuration will provide a map of the way sensory responses to individual syllables and activity correlated with syllable production are represented in nucleus HVc. Some possible outcomes are: 1) the perceptual and motor processing for each learned song syllable has an exclusive anatomical representation; 2) syllable representations show partial overlap; 3) syllable representations show complete overlap. These relationships may differ between the right and left hemispheres. If (1) or (2) applies, it may be possible to discern rules that govern the distribution and location of the representation of syllables, or their features. For example, similar sounding syllables, which share acoustic properties and/or motor programs may occupy nearby network space. An understanding of the anatomical representation of learned skills will help in revealing network conditions that encourage or limit learning. The research program described will ascertain the feasibility of the technical approaches the P.I. proposes which promise to yield new information on these important questions.